Our aim is to determine the three-dimensional structures of various forms of the thyroid hormone receptor. We have succeeded in determining the structure of the ligand-binding domain of the human thyroid hormone receptor beta isoform complexed to the thyroid hormone, triiodothyroacetic acid. Our next objective is to obtain the structure of the full-length receptor to understand how the ligand binding domain works together with the DNA-binding and N-terminal transactivation domains. The graphics facility at the Computer Graphics Laboratory has served as an essential resource to allow us to view the structures we obtain to develop models of how the protein functions.